Day: 10 July 2019

So in my last post I left you with the pier being fitted, this is just the start of the journey to be able to place the mount and telescope OTA’s Optical Tube Assembly on top. All of that would require power! And to fix all the power to the pier I needed a piece of wood which I had handy in the garage.

Once fitted this became one of two panels within the dome. We really wanted to keep the power and data and associated cables to two places. This would have a the MEII power supply at the top, a power strip to the right, the master power coming in from below and to a 2-way switch, there would be additions to this later.

The other board would sit by the incoming power and data supplies near the edge and Eastern side of the dome. A master switch for the lights, another power strip, a waterproof box for the MacMini, later to be changed to an Intel NuC due to software issues that we later realised we could fix 🙁 A 10 port USB hub (one of many), master Ethernet port for the incoming network connection from the house and providing 330MB into the dome and finally the master double socket for the electric.

Meanwhile the view from the Orangery was great, with the dome taking shape, although the plan is to have fencing and planting to soften the view for others.

The floor of the dome was painted with garage floor paint to seal in the concrete. It would transpire that the rubber matting I would later fit would need a DPC membrane under it to stop the build up of condensation caused by the cold concrete against the warmer rubber.

Meanwhile, we continued outside with building the supporting infrastructure, including a master soak-away and putting in the weather station pole and associated instruments. GingerGeek spent time helping dig the soak-away, we dug down either side of the concrete to the North and West which would be backfired with 20mm shingle.

A hole was then dug for the drainage for the dehumidifier, a must for any observatory. The plant pot has holes drilled in and was then filled with shingle to stop any soil from backfilling over time.

Round to the West of the dome we started to dig out the section for the soak-away.

I had purchased a sturdy large plastic container (I could stand on it without it flexing) and then drilled a fair amount of holes in it. It was then buried in the ground, connected to a standard large drainage pipe typically found taking waster from the house and connected that into it, completing the connection with several guns of mastic.

This was then connected to the plastic french drain we had previously dug out for and fitted.

Once this was done we laid the 20mm gravel to the entire North and West of the dome to cover, the plant pots as a reminder of where the soak-away was.

The pipe for the dehumidifier was covered with a standard plumbing pipe insulating cover to protect it from frost

The weather station fitting was a pole Bob had purchased and found brackets to fit to the fence to the West. The top instrument is a cloud monitor and rain detector from HiTech Astro and works well. We have it connected to the dome through a relay Bob put together so once cloud is detected or rain the dome closes and will not open unless you override in the software. The instrument to the right is the Sky Quality Meter provided by GingerGeek and is fantastic and telling you how dark it is and when my neighbours put their lights on or God forbid don’t turn them off all night …….. A further instrument was added later for an All Sky Camera which is a ZWO ASI120MC that Bob placed inside a dome and then connected through

So the dome was built in a day, which was clearly quicker than Rome 🙂 The video of the construction can be seen below. The new Orangery is to the right and the building mess within my garden is apparent.

With all the planning, I was always slightly nervous the cable pipes we had now concreted in place would not be in the correct positions. I required a set outside the dome, a set just inside where the electrics and computers would sit and a set near the pier. Fortunately I was pleased I measured twice 🙂

As you can see above the pier was fitted centrally which is what I wanted rather than offset as some suggest. The pier was a standard pulsar pier and took some time after fitting by Pulsar themselves to settle. As can be seen below, they fitted rods and bolts to secure and used a resin in the holes drilled.

This was different than my last observatory where I used long 12″ bolts. After tightening with a spanner the pier seemed secure but upon placing weight on it it started to move. I then tightened to the point where it was still vibrating a lot. I left a week to settle then came back with a torque wrench to tighten again. This drew the bolts out by about an inch which told me the resin had not gone off. Another week went by and I tightened a little more, this time the wrench kicked in with clicking and the bolts held, the pier stopped vibrating and all is finally well including the top plate fitted but Pulsar with a standard Meade pre drilled pattern.

I asked for the pier to be central and gave the Pulsar team the direction for North using a compass on my phone and checking with a traditional compass. Hopefully this would get me near the North Celestial pole once we fitted the Paramount MEII mounting plate we had. It turned out a few new holes needed to be drilled in our slightly used plate which to be fair was used for previous telescope mounts including a Meade 16″, Skywatcher EQ6, Paramount ME and now the MEII.

You can see Bob’s name proudly punched into the aluminium as well as the original manufacturing date of 2008.

Ok so it’s been a while, well more than a while, as Douglas Adams once said, ‘you thought it was a long way down the road to the chemist’ well I can tell you it’s a long road to building a commissioning an off the shelf observatory too! So even though the observatory is nearly complete I though I would share the build experience here on this very blog.

So it’s not been helped by the weather, it’s not been helped by the other building work on the house and it’s definitely not been helped by working so much either. The Ripton Windows team, incidently who are building a lovely Orangery for me as well as some other works, were also good enough to take on building the base and laying the electrics and network access.

The base for the pier was a single discrete 1m cube of concrete and surrounding that a slab of concrete of 3m square and 150mm deep. This was so the pier is isolated from any vibrations from the dome rotating or people walking about inside the dome.

The team from Ripton took a few days to dig the hole, pour the concrete in a couple of stages and then we had many weeks for it to set due to a delay in the Pulsar 2.7m dome arriving for install. I also laid a shingle surround to act as a french drain and included a homemade soaraway, more pictures later.

Work started with digging out from the outside in using a JCB, the team did a quick and good job, considering all the clay.

After some rain holding off the final dig, the team managed to dig out the rest of the base including the much deeper but separate 1m cube.

Scalpings were then laid and shuttering to act as a former for the central cube was fitted, this included DPC to help keep the cube from being effected by the surrounding area. PVC piping was also added before the mix was poured for the data and electric cable runs.

Before long the concrete was poured for both the inner and outer segments, now you can see the level below ground to which we dug to make sure we were inside the planning rules for the area.

Creating my very own stone henge, allowed me to see where the dome would finally come to.

I then went one stage further and placed a plastic pipe vertically to see the height of the final dome once fitted.

Finally my favourite electrician Steve fitted the main power to the outside and included CAT6 cable back to the main fibre hub for me.

This was run under the ground through plastic pipe, even though the cable was armoured, in case we wanted to run additional cables later.